The person who has been approached will always signal the other’s presence in some way…a sign. This signal is not like a train whistle, however, more a subtle body language which you can learn to recognize. For example, he or she simply may look up, move over to make room, nod slightly, or signal with a glancing eye contact.
A display of total obliviousness to the one who is approaching generally indicates lack of interest altogether. Don’t be discouraged. But if the one you approached shows absolutely no interest, then it’s time to re-group and try again. But let’s say the approach works. You have your positive acknowledgement, now what? Time to talk